What is the treatment for bradycardia (low heart rate)?

From the Guidelines

Treatment for symptomatic bradycardia should prioritize atropine administration, typically given as 0.5-1mg IV, which can be repeated every 3-5 minutes up to a maximum of 3mg, as recommended by the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1. The primary goal of treatment is to increase heart rate and alleviate symptoms such as dizziness, fatigue, or fainting.

• Atropine is the first-line medication for symptomatic bradycardia, with a dose range of 0.5-2 mg and a half-life of approximately 2 hours 1.
• For persistent bradycardia, temporary transcutaneous pacing may be required until a permanent pacemaker can be implanted, as outlined in the 2018 ACC/AHA/HRS guideline 1.
• Underlying causes like hypothyroidism, electrolyte imbalances, or medication side effects should be addressed, with hypothyroidism treated with levothyroxine, starting at 25-50mcg daily and adjusting based on thyroid function tests.
• If medications like beta-blockers or calcium channel blockers are causing bradycardia, dosage adjustment or medication changes may be necessary.
• For asymptomatic bradycardia, especially in physically fit individuals, no treatment may be needed as a lower resting heart rate can be normal. The treatment approach should be individualized based on the severity and underlying cause of bradycardia, with the goal of improving symptoms and preventing complications, as supported by the 2018 ACC/AHA/HRS guideline 1.

From the FDA Drug Label

Atropine-induced parasympathetic inhibition may be preceded by a transient phase of stimulation, especially on the heart where small doses first slow the rate before characteristic tachycardia develops due to paralysis of vagal control Adequate doses of atropine abolish various types of reflex vagal cardiac slowing or asystole The drug also prevents or abolishes bradycardia or asystole produced by injection of choline esters, anticholinesterase agents or other parasympathomimetic drugs, and cardiac arrest produced by stimulation of the vagus. Atropine also may lessen the degree of partial heart block when vagal activity is an etiologic factor In some patients with complete heart block, the idioventricular rate may be accelerated by atropine; in others, the rate is stabilized.

Low heart rate treatment: Atropine can be used to treat low heart rate (bradycardia) by increasing the heart rate.

• Key benefits: Atropine can abolish reflex vagal cardiac slowing, prevent or abolish bradycardia, and accelerate the idioventricular rate in some patients with complete heart block.
• Important consideration: Atropine may have a transient phase of stimulation, especially on the heart, where small doses first slow the rate before characteristic tachycardia develops due to paralysis of vagal control 2

From the Research

Low Heart Rate Treatment

• Low heart rate, also known as bradycardia, is a condition where the heart rate is lower than 60 beats per minute 3.
• It can be caused by various factors, including sinus, atrial, or junctional bradycardia, or problems with the conduction system, such as an atrioventricular block 3, 4.
• Symptoms of bradycardia can include syncope, dizziness, chest pain, dyspnea, or fatigue, and it is essential to determine if bradycardia is the cause of the patient's symptoms 3.

Treatment Options

• In the acute setting, symptomatic patients can be treated with atropine, and percutaneous pacing can be used as a bridge to definitive treatment 3.
• The only therapy for persistent bradycardia is the placement of a permanent pacemaker, especially for symptomatic patients with sick sinus syndrome and high second- or third-degree atrioventricular blocks 3, 5.
• Temporary and permanent pacing is now readily available, which has improved the morbidity and mortality associated with bradyarrhythmias 4.
• Management of bradycardia is based on the severity of symptoms, the underlying causes, presence of potentially reversible causes, presence of adverse signs, and risk of progression to asystole 6.

Management Strategies

• Various management strategies for symptomatic bradycardia have been compared, including observation, non-invasive management, early permanent pacemaker implantation, and delayed permanent pacemaker implantation 5.
• Adverse events were similar in patients who underwent early compared to delayed permanent pacemaker implantation, whereas adverse events were higher in patients who received temporary transvenous pacing 5.
• Weekend admissions were associated with increased temporary transvenous pacing, prolonged median time to permanent pacemaker implantation, and prolonged median length of stay 5.